Tonight, a heart-pounding "20/20" exclusive. Two little boys. Suddenly gone. Abducted by their own mother and her two ex-husbands, the boys' fathers begin an international manhunt to find them. Tonight, we take you inside that hunt for a fugitive mom like you have never seen before. We're there for the calls, the clues and the shocking video that disguises and you'll see what happens when we finally track down that mother on the run. Okay, once upon a time -- Reporter: This is the story of two beautiful little boys. Two brothers. Like so many children across America tonight, they are boys who try to push the limits at bedtime. This is jerry. It's time to go to bed. No, it's not. Yes, it is. It's almost 8:30. Guess what, no. Reporter: And there's Sasha, laughing here as he jumps on the trampoline. But the laughter from both boys goes silent. They vanish, and what follows is the international hunt to find them. And we're there as this case breaks wide open. But to understand how and why they disappeared in the first place, you have to go back to the Hollywood hills where scripts and screenplays are filled with fictional family drama. But right here in Los Angeles, two different fathers finding themselves in the middle of a real-life horror. For 18 months, both of them asking where are their sons? Those boys? And will the mother who took them, the woman each of them were once married to, ever be found? Jerry is everything to me. Without him, I can't live, I can't breathe. Reporter: Can you hear his voice still? Oh of course. It's strange because I feel like I'm with him all the time and except he's not here. Reporter: The last time Larry Hummel saw his son Sasha, he was just 3 years old. He always said I want to go on the purple dinosaur. He wanted a suit, he wanted to dress up, so we got suits. Reporter: Bob Pfeifer last saw his son, jerry had just turned 9. No, it tears at the core of everything that one stands for and knows about. Reporter: This L.A. Story actually began 6,000 miles away from California during a visit to Prague, when bob Pfeifer meets a stunning young woman who had American dream. Her name, maria misejova. Oh, she was beautiful girl. Very tall, athletic, blonde, blue eyes. Beautiful girl. Reporter: An accomplished runner she tells bob she's training to join the olympic team from her native Slovakia. And that she's planning for medical school. What did you see in her? Innocence. I was living in Hollywood, a town filled with the disingenuous. And I thought I met an innocent person. Reporter: And bob, a Hollywood insider is attractive to her too. A high-level record executive in the '90s, he then works in the booming video game industry. But something is missing. He is ready for a family, and so is she. So you married in July and she was pregnant within a couple of months. Yes. And was there excitement? I thought there was. Reporter: Maria moves to los Angeles, but the love story born in Prague - begins to sour even before the baby arrives. It starts to fall apart? Everything I thought she was, was false. Reporter: In fact, bob has already filed for divorce by the time their son jerry is born. And what would follow is a bruising battle over custody of their little boy, caught in the middle watching it all unfold. Did they live happily ever after? Well, they lived, no so happily. Was it contentious, or -- It was contentious, but I was very much involved in my son's life. Reporter: Bob's love life is unraveling and it seems his professional life is too. He finds himself facing charges and pleading to a felony in a high-profile case, the pellicano wiretapping case. And when you look back on it, what, what do you think? Regret. Reporter: Pfeifer ends up helping the prosecution and later, judges decide his past should not get in the way of custody of his little boy. And as it turned out, beautiful maria has blemishes too. Her friends say they see the wholesome, health-conscious mom. But others see a different side, a woman who enjoys the los Angeles nightlife company of wealthy men and there are questions about where she's getting her cash. A judge at one point saying, she showed an appalling lack of credibility. There are at least two personalities -- you have the whole foods bio, organic, cotton only, and then you have the party, drugs, alcohol. So these were two very different images? Reporter: They finally settle on sharing custody of jerry. Bob is tickled and so is his boy. Maria, meanwhile, moves on with her life. Meeting a new man. Larry Hummel, a Hollywood voice-over agent, and like bob before him, falls head over heels for the stunning Slovakian. Do you remember proposing to her? It was on my birthday and I said that, that the most joy that I could for my birthday would be if you would marry me. And she said? She said yes. Reporter: She says a lot of other things too. For one, that her name is "Maya," no longer going by maria. What did she tell you about her background, her life? She said that she was a medical student. She said her mother was a doctor in Prague. Reporter: How much of that was true? Very little of it. But you had no idea that you were married to a mystery woman? Correct. Reporter: And just like bob before him, now Larry and maria are expecting a baby. And soon another nasty break up too. She was very much about material things, and she had to have the best Stoller. Reporter: Maria leaves him, and Larry is crushed. But you were having a hard time with the break up? Oh for sure. It was -- it took a toll on me. Reporter: He says maria tells him Sasha might not even be his son the break up he admits leads to a mental breakdown. Larry so heart sick reaches out to an unlikely ally, the first husband, bob, who has heard it all before. It was like, having a mentor in the situation. And I said, you don't understand, you are at war. She made some serious allegations about you. Mm-hmm. She said you were abusive. Not true. Controlling. Not true. A drug addict. Not true. And then the custody battle. Yes. Reporter: Now the sequel the second custody battle to come. Maria wants full custody of her youngest son Sasha. But Larry wants Sasha too. And like the first husband, Larry, too, questions her mysterious income. The judges hear the allegations from both side and in the end still determine that both should take care of their son. You had Sasha during the week a couple of nights, you had him every other weekend? The proud dad taking this home video of his son on the drum set. But Larry has no idea how often he will soon be looking back at this video. The last one he would take of his boy Sasha. It is summer 2012, and maria has planned a summer vacation back to her native Slovakia with both of her boys. Did you know this family visit was coming, this trip back to Slovakia? Yes, she had done it before. Reporter: But on previous trips, maria had always come back. Not this time. Flight 9683 landing in Los Angeles and they are not on it. She was not on the plane she said she was gonna be on, and I just remember thinking, this is so surreal. Reporter: A mother and her two boys gone.

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